Search Talks

Search results

9421 - 9432 of 16889 Results

Long-time behavior of periodically driven isolated interacting quantum systems

Luca D'Alessio Boston University

May 13, 2014

PIRSA:14050073
Random models of inflation

Andrew Liddle University of Lisbon
May 13, 2014

PIRSA:14050007
Cosmology
Light-Cone Effects after Quantum Quenches and Excitations at Finite Entropy

Fabian Essler University of Oxford

May 13, 2014

PIRSA:14050072
Anatoli Polkovnikov - Deriving effective Floquet Hamiltonians in interacting systems using the Magnus expansion

May 13, 2014

PIRSA:14050071
The quest for self-correcting quantum memory

Olivier Landon-Cardinal California Institute of Technology
May 12, 2014

PIRSA:14050028
Quantum Information
Dynamical analogue quantum simulators

Jens Eisert Freie Universität Berlin

May 12, 2014

PIRSA:14050068
Quantum Quenches in Thermodynamic Limit

Marcos Rigol Pennsylvania State University

May 12, 2014

PIRSA:14050067
TBA

Eugene Demler Harvard University

May 12, 2014

PIRSA:14050065
Curvature in Noncommutative Geometry

masoud khalkhali Western University
May 09, 2014

PIRSA:14050064
Mathematical physics
Bulk-Edge Correspondence in 2+1-Dimensional Abelian Topological Phases

Jennifer Cano University of California, Santa Barbara
May 09, 2014

PIRSA:14050011
Condensed Matter
On the role of the extra kinetic term coupling ƛ in classical Hořava-Lifshitz gravity

Luis Pires Radboud Universiteit Nijmegen
May 08, 2014

PIRSA:14050061
Quantum Gravity
Black holes without Lorentz symmetry

Thomas Sotiriou University of Nottingham
May 08, 2014

PIRSA:14050002
Strong Gravity

Long-time behavior of periodically driven isolated interacting quantum systems

Luca D'Alessio Boston University

May 13, 2014

PIRSA:14050073

We show that generic interacting quantum systems, which are isolated and finite, periodically driven by sudden quenches exhibit three physical regimes. For short driving periods the Floquet Hamiltonian is well approximated by the time-averaged Hamiltonian, while for long periods the evolution operator exhibits properties of random matrices of a Circular Ensemble (CE). In-between, there is a crossover
regime. We argue that, in the thermodynamic limit and for nonvanishing driving periods, the evolution operator always exhibits properties of CE random matrices. Consequently, driving leads to infinite temperature at infinite time and to an unphysical Floquet Hamiltonian.
Random models of inflation

Andrew Liddle University of Lisbon
May 13, 2014

PIRSA:14050007
Cosmology
Rather than writing down specific functional forms, one can generate inflation models via stochastic processes in order to explore generic properties of inflation models. I describe our explorations of the phenomenology of randomly-generated multi-field inflation models, both for canonical fields and for a braneworld-motivated scenario. Implications of some recent observational results, including BICEP2, will be discussed.
Light-Cone Effects after Quantum Quenches and Excitations at Finite Entropy

Fabian Essler University of Oxford

May 13, 2014

PIRSA:14050072
Anatoli Polkovnikov - Deriving effective Floquet Hamiltonians in interacting systems using the Magnus expansion

May 13, 2014

PIRSA:14050071
The quest for self-correcting quantum memory

Olivier Landon-Cardinal California Institute of Technology
May 12, 2014

PIRSA:14050028
Quantum Information
A self-correcting quantum memory is a physical system whose quantum state can be preserved over a long period of time without the need for any external intervention. The most promising candidates are topological quantum systems which would protect information encoded in their degenerate groundspace while interacting with a thermal environment. Many models have been suggested but several approaches have been shown to fail due to no-go results of increasingly general scope. In a nutshell, 2D topological models and many 3D topological models have point-like excitations which propagate freely and change the groundstate at any non-zero temperature. A recent suggestion is to introduce effective long-range interactions between those point-like excitations. In this presentation, I will first explain the desiderata for self-correction, review the recent advances and no-go results, and describe the current endeavours to define a self-correcting system in 2D and 3D. Time permitting, I will briefly present our recent work on the thermal instability of models which aim to introduce effective long-range interactions between point-like excitations (joint work with Beni Yoshida, John Preskill and David Poulin).
Dynamical analogue quantum simulators

Jens Eisert Freie Universität Berlin

May 12, 2014

PIRSA:14050068

Complex quantum systems out of equilibrium are at the basis of a number of long-standing questions in physics. This talk will be concerned on the one hand with recent progress on understanding how quantum many-body systems out of equilibrium eventually come to rest, thermalise and cross phase transitions, on the other hand with dynamical analogue quantum simulations using cold atoms [1-4]. In an outlook, we will discuss the question of certification of quantum simulators, and will how this problem also arises in other related settings, such as in Boson samplers [5,6]. [1] S. Braun, M. Friesdorf, S. S. Hodgman, M. Schreiber, J. P. Ronzheimer, A. Riera, M. del Rey, I. Bloch, J. Eisert, U. Schneider, arXiv:1403.7199.
[2] M. Kliesch, M. Kastoryano, C. Gogolin, A. Riera, J. Eisert, arXiv:1309:0816.
[3] S. Trotzky, Y.-A. Chen, A. Flesch, I. P. McCulloch, U. Schollwoeck, J. Eisert, I. Bloch, Nature Physics 8, 325 (2012).
[4] A. Riera, C. Gogolin, M. Kliesch, J. Eisert, in preparation (2014).
[5] C. Gogolin, M. Kliesch, L. Aolita, J. Eisert, in preparation (2014) and arXiv:1306.3995.
[6] S. Aaronson, A. Arkhipov, arXiv:1309.7460.
Quantum Quenches in Thermodynamic Limit

Marcos Rigol Pennsylvania State University

May 12, 2014

PIRSA:14050067

Studies of the quantum dynamics of isolated systems are currently providing fundamental insights into how statistical mechanics emerges under unitary time evolution. Thermalization seems ubiquitous, but experiments with ultracold gases have shown that it need not always occur, particularly near an integrable point. Unfortunately, computational studies of generic (nonintegrable) models are limited to small systems, for which arbitrarily long times can be calculated, or short times, for which large or infinite system sizes can be solved. Consequently, what happens in the thermodynamic limit after long times has been inaccessible to theoretical studies. In this talk, we introduce a linked-cluster based computational approach that allows one to address the latter question in lattice systems. We provide numerical evidence that, in the thermodynamic limit, thermalization occurs in the nonintegrable regime but fails at integrability. A phase transition-like behavior separates the two regimes.
TBA

Eugene Demler Harvard University

May 12, 2014

PIRSA:14050065
Curvature in Noncommutative Geometry

masoud khalkhali Western University
May 09, 2014

PIRSA:14050064
Mathematical physics
After the seminal work of Connes and Tretkoff on the Gauss-Bonnet theorem for the noncommutative 2-torus and its extension by Fathizadeh and myself, there have been significant developments in understanding the local differential geometry of these noncommutative spaces equipped with curved metrics. In this talk, I will review a series of joint works with Farzad Fathizadeh in which we compute the scalar curvature for curved noncommutative tori and prove the analogue of Weyl's law and Connes' trace theorem. Our final formula for the curvature matches precisely with the one computed independently by A. Connes and H. Moscovici. I will then report on our recent work on the computation of scalar curvature for noncommutative 4-tori (which involves intricacies due to violation of the Kähler condition). We show that metrics with constant curvature are extrema of the analogue of the Einstein–Hilbert action. A purely noncommutative feature in these works is the appearance of the modular automorphism from Tomita–Takesaki theory of KMS states in the final formulas for the curvature.
Bulk-Edge Correspondence in 2+1-Dimensional Abelian Topological Phases

Jennifer Cano University of California, Santa Barbara
May 09, 2014

PIRSA:14050011
Condensed Matter
The same bulk two-dimensional topological phase can have multiple distinct, fully-chiral edge phases. We show that this can occur in the integer quantum Hall states at fillings 8 and 12 with experimentally-testable consequences. We also show examples for Abelian fractional quantum Hall states, the simplest examples being at filling fractions 8/7, 12/11, 8/15, 16/5. For all examples, we propose experiments that can distinguish distinct edge phases. Our results are summarized by the observation that edge phases correspond to lattices while bulk phases correspond to genera of lattices. Since there are typically multiple lattices in a genus, there are usually many stable fully chiral edge phases corresponding to the same bulk. We show that fermionic systems can have edge phases with only bosonic low-energy excitations and discuss a fermionic generalization of the relation between bulk topological spins and the central charge. The latter follows from our demonstration that every fermionic topological phase can be represented as a bosonic topological phase, together with some number of filled Landau levels. Our analysis also leads to a simple demonstration that all Abelian topological phases can be represented by a Chern-Simons theory parameterized by a K-matrix.
On the role of the extra kinetic term coupling ƛ in classical Hořava-Lifshitz gravity

Luis Pires Radboud Universiteit Nijmegen
May 08, 2014

PIRSA:14050061
Quantum Gravity
We study the classical constraint algebra of Hořava-Lifshitz gravity, where due to the breaking of 4d diffeomorphism symmetry, there is a new dimensionless coupling absent in GR and whose role is not yet clear. Starting from two apparently contradictory results, we show how the role of the extra coupling differs between the projectable and non-projectable versions of the theory. In particular, we see how in the latter, it gives rise to a non-trivial constraint algebra, akin to the conditions seen in the CMC gauge of GR.
Black holes without Lorentz symmetry

Thomas Sotiriou University of Nottingham
May 08, 2014

PIRSA:14050002
Strong Gravity
Our current definition of what a black hole is relies heavily on the assumption that there exists a finite maximum speed of propagation for any signal. Indeed, one is tempted to think that the notion of a black hole has no place in a world with infinitely fast signal propagation. I will use concrete examples from Lorentz-violating gravity theories to demonstrate that this naive expectation is not necessarily true.

Title	Date	Collection	Type	Info
Long-time behavior of periodically driven isolated interacting quantum systems	2014‑05‑13	Quantum Many-Body Dynamics	Conference	View details
Random models of inflation	2014‑05‑13	Cosmology and Gravitation	Scientific Series	View details
Light-Cone Effects after Quantum Quenches and Excitations at Finite Entropy	2014‑05‑13	Quantum Many-Body Dynamics	Conference	View details
Anatoli Polkovnikov - Deriving effective Floquet Hamiltonians in interacting systems using the Magnus expansion	2014‑05‑13	Quantum Many-Body Dynamics	Conference	View details
The quest for self-correcting quantum memory	2014‑05‑12	Perimeter Institute Quantum Discussions	Scientific Series	View details
Dynamical analogue quantum simulators	2014‑05‑12	Quantum Many-Body Dynamics	Conference	View details
Quantum Quenches in Thermodynamic Limit	2014‑05‑12	Quantum Many-Body Dynamics	Conference	View details
TBA	2014‑05‑12	Quantum Many-Body Dynamics	Conference	View details
Curvature in Noncommutative Geometry	2014‑05‑09	Quantum Gravity	Scientific Series	View details
Bulk-Edge Correspondence in 2+1-Dimensional Abelian Topological Phases	2014‑05‑09	Quantum Matter	Scientific Series	View details
On the role of the extra kinetic term coupling ƛ in classical Hořava-Lifshitz gravity	2014‑05‑08	Quantum Gravity	Scientific Series	View details
Black holes without Lorentz symmetry	2014‑05‑08	Strong Gravity	Scientific Series	View details

Search Talks

Format results